androidx.camera.view.PreviewView Causes java.lang.NullPointerException in Xamarin.Android Designer

Question

I am working on adding an androidx.camera.view.PreviewView to my Xamarin.Android app, but it displays a java.lang.NullPointerException in the Xamarin.Android Designer in Visual Studio 2022. The Details: displayed in the Designer are as follows:

android.hardware.display.DisplayManager.registerDisplayListener(DisplayManager.java:414)
androidx.camera.view.PreviewView.startListeningToDisplayChange(PreviewView.java:970)
androidx.camera.view.PreviewView.onAttachedToWindow(PreviewView.java:299)
android.view.View.dispatchAttachedToWindow(View.java:18347)
android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3397)
android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3404)
android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3404)
android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:3404)
android.view.AttachInfo_Accessor.setAttachInfo(AttachInfo_Accessor.java:42)
com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:330)
com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:394)
com.android.tools.idea.layoutlib.LayoutLibrary.createSession(LayoutLibrary.java:271)
mono.android.DesignerSession.loadInternal(DesignerSession.java:273)
mono.android.DesignerSession.lambda$load$0(DesignerSession.java:223)
mono.android.MonoDroidBroker.executeInMonoDroidContext(MonoDroidBroker.java:76)
mono.android.DesignerSession.load(DesignerSession.java:223)
mono.android.DesignerSession.processMessage(DesignerSession.java:676)
mono.android.MessageListener.executeMessage(MessageListener.java:88)
mono.android.MessageListener$Runner.run(MessageListener.java:44)
java.lang.Thread.run(Thread.java:748)

The exact xml of the PreviewView is as follows:

<androidx.camera.view.PreviewView android:id="@+id/pvCurrent" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_column="0" android:layout_row="0" tools:layout_width="match_parent" tools:layout_height="150dp" tools:background="@Color /Three"/>

I am not sure what to do, since this is my first time with PreviewView & it is a design time exception. What is the problem?

Answer 1

Hello,

There is an official sample for how to use androidx.camera.view.PreviewView in Xamarin.Android, please refer to Xamarin.CameraX1.

It's Xamarin.Android version to implement the official Google guide of Getting Started with CameraX.

Best Regards,

Alec Liu.

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